• The KSFM Journal of Fluid Machinery
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• v.14 no.3
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• pp.33-38
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• 2011

Medicated water electrolysis apparatus, which electrolyzes water into acidic water and alkaline water, was in the spotlight as becoming known the effect of alkaline water. It is known as good for health as removing active oxygen in the human's body and promoting digestion. But, the customers could not get that desired water temperature because these apparatuses are directly connected with a water pipe. So, the cooling system was developed for controlling the temperature of the alkaline water. One of the typical way is to store water in water tank and control the temperature. But, in this way, storing water can be polluted impurities coming from outside. For protecting this pollution, the cooling system based on indirect heat exchange method through phase change between water and ice was developed. In this study, we have calculated efficiency of the cooling system with phase change by experiment and commercial CFD(Computational Fluid Dynamics) code, ANSYS CFX. To consider the effect of latent heat that is generated by melting ice, we have simulated two phase numerical analyses used enthalpy method and found the temperature, velocity, and ice mass distribution for calculating the efficiency of cooling. From the results of numerical analysis, we have obtained the relationship between the cooling efficiency and each design factor.

• Journal of Korean Society of Water and Wastewater
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• v.33 no.4
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• pp.299-309
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• 2019

Waterworks facilities inevitably experience some amount of leakage even if there is a lot of investment or state-of-the-art technology that is applied such as DMA(District Metered Area) system construction, leakage detection, repair, pipe rehabilitation, etc. The primary reason is the leakage is naturally restored over time. In the UK, this restoration characteristic is defined as NRR(Natural rate of rise of leakage) and used to decision making for prioritizing active leakage control of DMAs. However, this restoration characteristic is well recognized, but researches on NRR in the water distribution system are insufficient in Korea. In this study, the estimation method of NRR was developed suitable for applicating in Korea considering of SCADA data, water infrastructure, and water usage patterns by modification of the UK's NRR method. The proposed method was applied to 9 DMAs and verified it's applicability by comparing with the other water loss performance indicators. It is expected that the proposed method can be used to support decision making for sustainable NRW(Nor-revenue water) management in the water distribution system.

• Journal of Korean Society on Water Environment
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• v.27 no.6
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• pp.885-895
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• 2011

The purpose of this study was evaluated on achievement of the Target water quality (TWQ) with Load Duration Curve (LDC) as well as materials collected through the implementation of Total Maximum Daily Load (TMDL), targeting 41 unit watersheds in the Nakdong River Basin in korea, and examines the adequacy of the LDC method to evaluate the TWQ by comparing methods through current regulations. It aims to provide basic materials for TMDL development in Korea. This determination resulted from the fact that the measured data placed on the LDC mean that they are beyond TWQ in a certain condition of water flow when actually measured load values were displayed in a form of LDC. In addition to water quality surveys, it is considered that information on the level of damage in a water body by water flow grade can be utilized as a basic material to identify compliance with the total admitted quantity, and establish rational plans to improve water quality. This information helps in the identification of the degree of damage in water quality according to water flow.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2009.05a
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• pp.535-538
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• 2009

Auto Pilot is the system which move automatically the vessel through locating operation mode to automatic after entering operating course using a electronic chart or plotter. And water jet is the a propulsion system that make a power to push the vessel through spouting the accelerated water which is absolbed by the hole in the bottom of vessel. The water jet receive the effect of the depth of water lowly, it's acceletion efficiency is higher under high speed and have an advantage on vibrating and floating sound, so it's demand is increasing as new propulsion system. However, the signal systems of auto Pilot and water jet are defferant, we need the system to communicate between each system. We propose the interface system which communicate between Auto pilot and water jet efficiently in this journal.

• 한국신재생에너지학회:학술대회논문집
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• 2010.06a
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• pp.169.2-169.2
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• 2010

The research assesses the performance of the water-to-water heat pump system installed in Cheongju water treatment plant for cooling and heating ventilation. In summer season monthly averaged COP is ranged from 3.85 to 4.56 according to the water source temperature, and the performance is increased as the raw water temperature is dropped. While, heating performance is increased for the high temperature water source, and the monthly averaged COP is changed from 2.92 to 3.82. The correlation of the water source temperature and the heat pump performance shows a linear tendency by the simple regression of average data. In heating, the COP of heat pump system linearly rises according to the water source temperature. In comparison, the COP in cooling linearly reduces as the raw water temperature is raised. The goodness of fit at the simple regression shows the coefficient of determination 82% in cooling, 46% in heating. The electric cost of water-to-water heat pump is reduced by 40% compared to that of air source heat pump.

• Proceedings of the Korean Society of Agricultural Engineers Conference
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• 2001.10a
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• pp.470-474
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• 2001

A pilot study was performed at the experimental field of Konkuk University in Seoul, to examine the waste water treatment using constructed wetland and pond system. The effluent of the wetland system in winter often exceeded effluent water quality standards for sewage treatment plant, therefore, pond system could be applied to additional system. As a result, removal rate of $BOD_{5}$, SS was 84.4%, 81.5% and effluent concentration was 4.6mg/L and 5.0mg/L respectively, when surface water of pond system was discharged in March. So we concluded that pond system stored wetland effluent in winter and discharged surface water of pond system in March, so met water quality standard.

• Journal of Digital Convergence
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• v.7 no.3
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• pp.103-111
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• 2009

In this paper, we introduce automatic meter reading system for tap water. The system is composed of automatic meter, router using RF and CDMA network, and data server. This system will easily extend to fire detect, gas, and electric charge meter system. In addition, this system will be used to monitoring a water leak and human which live in solitude. Proposed system is installed at Gimhae-City and Gijang-gun. As a result of the automatic meter reading system for tap water, The leak of water and complain of user is decreased. But The building cost is still an obstacle to expand into entire city.

• Journal of the Korean Society of Visualization
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• v.20 no.3
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• pp.117-127
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• 2022

The present study has investigated the performance of hydrogen gas generators for inhalation purposes based on polyelectrolyte membrane water electrolysis (PEMWE). The system applied two watering methods. One is pumped water (pumping system) and the other is gravity-fed water without a pump (non-pumping system). The cell efficiencies were compared by measuring the cell voltage and temperature in the hydrogen gas generator, respectively. The results show that the cell voltage and temperature increase with the cell current. The cell temperature is lower in the pumping system than that in the non-pumping system at a given cell current. Even though the amount of hydrogen production is the same regardless of the pumping system, the cell efficiency of the hydrogen gas generator in the non-pumping system is better than that in the pumping system.

• The Magazine of the Society of Air-Conditioning and Refrigerating Engineers of Korea
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• v.11 no.4
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• pp.6-18
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• 1982

The performance of two typical types of solar hot water heating system was tested in Seoul. Types of systems studied are single-tank internal external heat exchanger system and single-tank internal heat exchanger system. Comparing to experimental results, a transient system simulation program was made to analyze the performance of the selected system. The climate data, Standard Weather Year for Seoul, required for the simulation was provided. Computer simulations were used to estimate the effect of significant parameters upon system performance. The followings are obtained. 1. In the domestic solar water Heating system, the value $20-40kg/m^2\;h$ for flow rate through the collector is much better than the recommended value $72kg/m^2\;h$ in the solar heating system. 2. The effectiveness of collector heat exchanger and storage tank size are found to have only a small effect upon system performance. 3. The hot water draw pattern has a significant effect on system performance. A higher system efficiency achieved when draw-off occurred around noon than when it occurred around early morning. Using the above results, the reference solar hot water system which provides $300\ell$ of hot water per day, was selected as a guide for designer. And simplified graphical method was developed based on the modified f-chart method to determine required collector area. When the system design parameters of the proposed system differs from the reference system, required collector area can be calculated from area adjustment factors.

• KIEAE Journal
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• v.2 no.3
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• pp.25-32
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• 2002

The demand for water in a city area has enormously increased due to the concentration of population and improvement of the living quality. In this reason, the water shortage and the pollution by city sewage seem to be inevitable. For saving city water and meeting the demands from the city, the wastewater recycling system can be used, which makes used water reusable by a certain purification process. In Korea, the application of a wastewater recycling system to the buildings has continuously been adopted since its first appearance at the Lotte World Complex in 1989. However, the system has not been in fashion because of its high cost and users' negative attitude against recycled water. A research based on literature review and a case study for a recycling water system was carried out and an estimation and evaluation model was proposed. The results from the present study suggest that the optimal size of the recycling water system should be designed within 30-40% of total water demand in a building. Also, it was found that economic benefits could be expected within the payback period of 5.3 years by securing the operation rate over 70%.